This invention relates to the construction of a shoe, and more particularly to such shoes, preferably of the sporty type, in which the uppers are made of leather, suede, or of a generally smooth-surfaced plastics material such as polyurethane, PVC (polyvinyl chloride) which is not readily bonded to rubber, and an outer member encloses the joints of the lasted sole structure to afford protection against scuffing and resistance to the penetration of moisture.
It has been known heretofore to construct shoes with leather uppers or with uppers made of various plastics materials such as PVC and polyurethane and with an outer sole made of rubber or a rubber-like material. However, certain difficulties manifest themselves subsequent to the lasting of such uppers when an outer enclosing rubber or rubber-like member is to be adhesively secured to the shoe. In order to obtain the requisite adhesion between the outer member, which may be a foxing strip or a simulated foxing strip, and the upper, extensive treatment of the uppers in a preliminary processing step was required. Such processing customarily took the form of either roughening the area of the upper to be adhered to by the outer member, chemically treating such area or otherwise modifying the surface characteristics of the upper to provide the desired bonding between the materials. Frequently, especially when roughening of the upper was performed, the upper was reduced in thickness or otherwise altered which resulted in an area of weakness at the very location where the shoe is subjected to bending and flexure stresses when in use. This has often led to a reduction in the useful life of the shoe and has necessitated periodic shoe repair and maintenance. Further, in order to vulcanize leather shoes with such prior constructions it has been necessary to pre-treat the leather, such as by tanning, in order to enhance the adhesive characteristics of the leather by removal of or neutralization of certain fats and/or oils which adversely affected adhesion.
Where the outer enclosing member is applied to the shoe in an automatic operation, such as by injection molding, the rubber or rubbery material of the outer member migrates over the adjacent surface of the leather, necessitating a laborious and time-consuming leather cleaning sequence.
Still further, in shoe constructions where the upper is lasted into the inner sole by one of the conventional lasting techniques, the amount of leather or like material required to effectuate lasting added to the cost of the shoe and resulted in the unnecessary consumption of a valuable material.
Culter in U.S. Pat. No. 1,622,860 issued Mar. 29, 1927 taught the securing of leather uppers to the crepe outer sole of a shoe by means of an intermediate strip made of fabric and saturated with rubber latex.
U.S. Pat. No. 2,024,167 to Kent, Jr. issued Dec. 17, 1935 discloses the use of an intermediate strip, of leather or a thin strong material, into which rubber has been ground or impregnated, and an edge barrier strip. However, the leather upper was lasted into the sole structure by being made of sufficient length to be turned under the inner sole.
Wherever employed in the claims or description of this invention the expression "leather or like material" is intended to include those materials which cannot be readily bonded to rubber without the use of a preparatory chemical treatment to remove or neutralize fats and/or oils present in the material or a mechanical surface-roughening treatment to enhance the adhesive characteristics of the material.